Search results for "Crystal system"
showing 10 items of 13557 documents
Synthesis, Structure, and Properties of BaVO2(AsO4): a New Vanadium Arsenate Containing the V2O42+ Core
1997
The new vanadium arsenate BaAsVO6 has been synthesized hydrothermally and structurally characterized by single-crystal X-ray diffraction, IR spectroscopy, and magnetic susceptibility measurements. It crystallizes in the monoclinic system, space group P21/c with unit cell parameters a = 5.645(1) A, b = 10.243(1) A, c = 8.945(1) A, β = 90.60(1)°, and Z = 2. The layered structure is built up from V2O42+ units and AsO43- anions, the AsO43- ligands being coordinated to two (V2O4)2+ units in both, terminal and bridging μ2-AsO43- fashion. The [VO2(AsO4)]2- layers are separated by Ba2+ cations. The V2O42+ unit has no precedence in oxo-vanadium chemistry.
The Crystal Structure of the THF Adduct of Monolithioferrocene
2015
Single crystals of [Fe(η5-C5H4)(η5-C5H5)]2Li2(thf)4 (1) were obtained from a tetrahydrofuran solution containing monolithioferrocene. The title compound crystallizes in the monoclinic space group P21 with a = 9.6589(5) A, b = 17.4285(9) A, c = 30.3116(15) A, β = 91.911(2)° and V = 5099.8(5) A3 with three independent molecules of 1. All individual molecules feature a non- symmetric almost planar Li2C2 four-membered ring with two shorter (2.118–2.215 A) and two longer Li–C distances (2.257–2.309 A). The lithium cations are each coordinated by two carbanionic atoms of two ferrocenyl substituents and two tetrahydrofuran molecules in a distorted tetrahedral fashion. All ferrocenyl moieties displ…
Increasing the Nuclearity of Magnetic Polyoxometalates. Syntheses, Structures, and Magnetic Properties of Salts of the Heteropoly Complexes [Ni3(H2O)…
1998
The rational synthesis and the structural and magnetic characterization of three different nickel clusters encapsulated in Keggin trivacant fragments are presented. The three complexes show how it is possible to increase the nuclearity of the clusters (from 3 and 4 to 9) by slightly changing the synthetic conditions. These three anionic clusters crystallize as mixed salts of K+ and Na+. The trimeric complex [Ni3(H2O)3PW10O39H2O]7- (Ni3) crystallizes in the triclinic space group P1 (a = 10.896(6) A, b = 12.869(5) A, c = 20.373(6) A, α = 94.67(6)°, β = 101.12(8)°, γ = 110.72(8)°, Z = 2) and presents a ferromagnetic triangular cluster. The tetranuclear complex [Ni4(H2O)2(PW9O34)2]10- (Ni4) cry…
Synthesis and Crystal Structure of a Novel Lamellar Barium Derivative: Ba(VOPO4)2·4H2O. Synthetic Pathways for Layered Oxovanadium Phosphate Hydrate…
1997
A unified synthetic strategy has allowed us to rationalize the preparative chemistry of the layered oxovanadium phosphates M(VOPO4)2·nH2O. Thus, we have been able to isolate as single phases with reasonable yields both all the previously characterized phosphates and a new solid containing Ba2+ cations as guest species as well as to prepare new related derivatives involving arsenate anions. In order to organize the experimental results, we have used two complementary models: a simple restatement of the partial charge model (PCM), and the valence matching principle (VMP) (derived from the bond valence method). The crystal structure of the new barium lamellar derivative, Ba(VOPO4)2·4H2O, has …
(NBu4)Ni(mnt)2: A novel bistable high temperature spin-Peierls-like system
2005
Abstract The title compound, tetrabutylammonium bis(1,2-dimercaptoethene-1,2-dicarbonirtilato-S,S′)-nickel (III) [henceforth (NBu4)Ni(mnt)2] undergoes a hysteretic phase transition that occurs at 172 K upon cooling. Crystallographic studies show that the phase transition is an order–disorder type involving one arm of the NBu 4 + cation. Both phases are monoclinic, space group C2/c with a = 30.860(3), b = 13.804(2), c = 15.678(2) A and β = 115.642(3)° with V = 6020.8(11) A3 at room temperature and with a = 31.073(3), b = 13.928(1), c = 14.414(1) A and β = 115.073(2)° and V = 5652.1(9) A3 at 84 K. In both phases, the anions form non-uniform stacks parallel to the crystallographic c direction.…
Über Germanium‐haltige Heterocyclen, IV. 2,2,4,4,6,6‐Hexaphenyl‐1,3,5‐trioxa‐2,4,6‐trigermacyclohexan, (Ph 2 GeO) 3 , eine monoplanare Zwischenstufe …
1982
Die Titelverbindung 1 wurde durch Hydrolyse von Ph2GeCl2 in acetonischer Losung gewonnen. Die Kristallstruktur wurde bestimmt und bis R = 0.049 verfeinert. Die Konformation des Ge3O3-6-Ringes ist monoplanar und bildet eine mogliche Zwischenstufe einerseits fur die Racemisierung von Twist-Wanne-Enantiomeren und andererseits bei der Sessel-Sessel-Inversion. Ein angeregter Zustand mit umlaufendem Null-Torsionswinkel wird als Alternative zur gangigen Lehrbuchdarstellung dieser Vorgange diskutiert. Die GeOAbstande und GeOGe-Winkel betragen 176–178 pm bzw. 128–130°. Die 1-Molekule sind im Kristall nach Art einer tetragonal-innenzentrierten Kugelpackung mit (10 + 4)-Koordination gepackt. On Hetero…
Molekül- und kristallstruktur von hexamethylcyclo-tristannaselenan [(CH3)2SnSe]3
1978
Hexamethylcyclotristannaselenane [(CH3)2SnSe]3 forms tetragonal crystals, space groups P41212, with a 986.5(2), c 1769.7(4) pm, Z 4. The complete X-ray structural analysis (two independent determinations) shows the six-membered ring to have a twist-boat conformation similar to [(CH3)2SnS]3. The SnSe2C2 tetrahedra are only slightly distorted, the mean bond distances being SnSe 253.1 (251.7⋯254.0(4)) pm, Sn C 2.13 (2.09⋯2.17(3)) pm. Conformational details are discussed.
Preparation, crystal structure, and infrared characterization of the first thiocyanato-oxy-antimonate(III) [(CH3)4N]2[Sb6O4(NCS)12]
1995
The salt [(CH3)4N]2[Sb6O4(NCS)12] is the first identified thiocyanato-oxy-antimonate(III) complex. Reported are details of the synthesis, relevant infrared data and its x-ray structure. The compound crystallizes in the triclinic space group P1 with Z = 2 (C10H12N7O2S6Sb3) and unit cell dimensions a = 11.314(6), b = 12.846(3), c = 8.679(2) A; α = 91.93(3)°, β = 90.31(3)° and γ = 99.13(3)°. It contains centrosymmetric [Sb6O4(NCS)12]2− anions packed with isolated tetramethyl-ammonium cations. The fundamental structural element of the anion is provided by the fusion of three SbOSbO rings forming a zig-zag portion of a ribbon, only slightly pleated. Peculiar is the unequivalence of the six thioc…
Crystal structures and magnetic properties of two- and three-dimensional malonato-bridged manganese(ii) complexes
2003
Two new manganese(II) compounds of formula [Mn(mal)(H2O)(2,4′-bpy)]n (1) and [Mn2(mal)2(H2O)2(4,4′-bpy)]n (2) (2,4′-bpy = 2,4′-bipyridine, 4,4′-bpy = 4,4′-bipyridine and H2mal = malonic acid) have been prepared and structurally characterized by X-ray crystallography. Their structures are made up of two- (1) and three-dimensional (2) arrangements of manganese atoms linked by carboxylate-malonate groups in the anti–syn bridging mode (1 and 2) and bis(monodentate) 4,4′-bpy (2). The 2,4′-bpy group in 1 acts as a monodentate ligand. Each manganese atom in 1 and 2 is six-coordinated with four carboxylate-oxygens in the equatorial plane and a nitrogen atom and a water molecule in the axial positio…
Synthesis and characterization of diorganotin(IV) derivatives of 2-mercaptopyridine and crystal structure of diphenyl pyridine-2-thiolatochlorotin(IV)
1994
Diorganotin(IV) derivatives of 2-mercaptopyridine (HSPy), R2Sn(SPy)2, R2SnCl(SPy) (R = Me, iPr, nBu, tBu, Cy, Ph) and Cy2SnBr(SPy), were obtained from R2SnX2 (X = Cl, Br) and NaSPy. Ph2SnCl(SPy) crystals, as determined by singlecrystal X–ray diffraction, are monoclinic in the space group P21/n. Tin forms with the bidentate SPy ligand a four–membered chelate ring with a short NSnS bite angle of 64.8(1)° leading to a heavily distorted trigonal–bipyramidal environment about tin. Apical Cl–Sn–N angle = 156.1(1)° equatorial C–Sn–C angle = 121.9(2)°. From 119Sn Mossbauer and IR data, analogous structures are inferred for the other solid compounds R2SnX(SPy), and distorted octahedral molecular str…